The present invention relates to a module for optical communication or an optical fiber device.
In a conventional module for optical communication, a metallic package receiving an end of an optical fiber and an optical element in a hermetic sealing manner is used. A replacement of the metallic package by a synthetic resin package is desired to decrease a producing cost of the module.
An object of the present invention is to provide a module for optical communication or an optical fiber device in which a reliability of an optical transmission between an optical fiber and an optical element is kept high without a significantly-precise relationship in position and attitude between the optical fiber and the optical element, and/or a metallic hermetic sealing.
According to the present invention, since in a module for optical communication comprising an optical fiber including an axial-end surface, and an optical element including an optical surface facing to the axial-end surface in such a manner that a light is transmitted between the optical surface and the axial-end surface, a transparent solid-state medium, for example, a synthetic resin or glass, is arranged between the optical surface and the axial-end surface so that the light is transmitted through the transparent solid-state medium between the optical surface and the axial-end surface, a volume of atmosphere including humidity between the optical surface and the axial-end surface is minimized to restrain a deterioration of the optical fiber and/or the optical element caused by the humidity. The transparent solid-state medium may be a high-rigidity or hard member such as glass or epoxy-resin, a low-rigidity or soft member an elastomer, a soft viscoelastic elastomer such as silicone resin or the like.
For restraining strongly the deterioration of the optical fiber (the axial-end surface) and/or the optical element (the optical surface) and/or preventing an undesirable reflection at the optical surface toward the axial-end surface, a contact between the transparent solid-state medium and the axial-end surface, and/or a contact between the transparent solid-state medium and the optical surface is effective. For preventing securely the deterioration of the optical fiber (the axial-end surface) and/or the optical element (the optical surface) and/or preventing the undesirable reflection at the optical surface toward the axial-end surface, it is preferable for the transparent solid-state medium to extend continuously or fill completely between the optical surface and the axial-end surface. For preventing securely the deterioration of the optical fiber (the axial-end surface) and/or the optical element (the optical surface) and making an optical characteristic between the optical surface and the axia-end surface constant and correct, it is preferable for the transparent solid-state medium to extend monolithically between the optical surface and the axia-end surface to cover monolithically both of the optical surface and the axial-end surface.
If the optical surface is prevented from extending perpendicularly to a direction of a longitudinal axis of the optical fiber or optical-light-proceeding axis of the optical fiber at the axial-end surface, the light from the axial-end surface is prevented from being reflected toward the axial-end surface by the optical surface.
If a refractive index of the transparent solid-state medium facing to or contacting the axial-end surface is more than that of the atmosphere to decrease a difference between that of the transparent solid-state medium and that of the axial-end surface or optical fiber, for example, not more than that of the optical fiber or axial-end surface, the light is restrained from being reflected or returned by the axial-end surface. If the refractive index of the transparent solid-state medium facing to or contacting the optical surface is more than that of the atmosphere to decrease a difference between that of the transparent solid-state medium and that of the optical element or optical surface, for example, not more than that of the optical element or optical surface, the light is restrained from being reflected or returned by the optical surface. The axial-end surface may extend substantially perpendicularly to the longitudinal axis of the optical fiber at the axial-end surface. The transparent solid-state medium, for example, a glass or synthetic resin, may comprise or be a substantially transparent silicone resin and/or a substantially transparent epoxy resin.
The optical element may perform through the optical surface at least one of emitting the light toward the axial-end surface so that the optical element generates an optical signal to be transmitted through the optical fiber and receiving the light from the axial-end surface so that the optical element generates an electric signal from the light transmitted through the optical fiber. The optical element may include a light generator and a light beam cross-sectional area expanding element arranged between the light generator and the axial-end surface to increase a cross-sectional area of the light (along an imaginary plane perpendicular to a proceeding axis or direction of the light) supplied to the axial-end surface in comparison with that of the light at the light generator, and the optical surface may be formed on the light beam cross-sectional area expanding element.
The optical fiber may be substantially surrounded at an axial-end thereof by the solid-state medium in an airtight sealing manner, so that the axial-end of the optical fiber is securely prevented from being deteriorated by the atmosphere.